Rosaria is the Covenant leader for Rosaria’s Fingers, the PvP Covenant. Located in the Cathedral of the Deep, her room can only be reached by climbing over the rafters high above the cathedral floor.

Rosaria also acts as the only source of a few very special services. You can respec your attributes completely by visiting her, and you can change your appearance. Both require Pale Tongues. You are limited to five respecs or rebirths on a single playthrough, but if you venture into new game territory, you can do so again.

There is a subplot involving Ringfinger Leonhard and his relationship with both you and Rosaria. If you follow Leonhard’s story up to the point of retrieving the Red Eye Orb from the Darkwraith in High Wall and then come to the Cathedral and join Rosaria’s Fingers, he appears just outside her chambers to greet you.

Later, after reaching the Profaned Capital bonfire or defeating Yhorm, if you return here, you will find Rosaria dead! Pick up the Black Eye Orb from her body and carry it with you to Anor Londo. In the room at the top of the cathedral there, past the Aldrich boss fight, the Black Eye Orb triggers, allowing you to invade Leonhard and slay him to recover Rosaria’s Soul. Return her soul and she revives as though nothing occurred.

Finally, joining Rosaria’s Fingers angers Sirris’ of the Sunless Realms. If you are pursuing her story fully, you cannot join Rosaria in the same playthrough.